ANNA-1 (anti-Hu) and ANNA-2 (anti-Ri) are screened by immunofluorescence and confirmed by immunoblot detection of antibody reactive with a 35-40 kDa (ANNA-1) or a 55 kDa (ANNA-2) neuronal protein. ANNA-1 is present in patients with paraneoplastic syndromes (paraneoplastic sensory neuropathy or paraneoplastic encephalomyelitis) most commonly associated with small-cell lung carcinoma (SCLC). ANNA-2 is present in patients with midbrain encephalitis, cerebellar ataxia, eye movement disorders (usually opsoclonus), and occasionally myelopathy. Neoplasms most often associated with ANNA-2 are breast carcinoma and SCLC. ANNA-1 and ANNA-2 may be detectable before the associated neoplasm is detectable.

ANNA antibodies are screened by IFA. If the IFA screen shows reactivity at 1:10, the specimen will be titered to endpoint and confirmed (Hu or Ri) by immunoblot.